Add use_v4l2_codec use flag to include v4l2 codec on x86 CrOS.

Because some trybots such as linux chromeos ozone use old linux
header files, use this flag to workaround chromium:446088 issue
to skip those trybots. So we can re-submit
https://codereview.chromium.org/826663002/. After 446088 is
fixed, this CL should be reverted.

BUG=445016
TEST=build squawks with this flag

Review URL: https://codereview.chromium.org/799543005

Cr-Commit-Position: refs/heads/master@{#310715}

content/common/BUILD.gn

@@ -281,12 +281,10 @@ source_set("common") {
   }
 
   if (is_chromeos) {
-    if (cpu_arch == "arm" && use_x11) {
+    if ((cpu_arch == "arm" && use_x11) || use_v4l2_codec) {
       sources += [
-        "gpu/media/exynos_v4l2_video_device.cc",
-        "gpu/media/exynos_v4l2_video_device.h",
-        "gpu/media/tegra_v4l2_video_device.cc",
-        "gpu/media/tegra_v4l2_video_device.h",
+        "gpu/media/generic_v4l2_video_device.cc",
+        "gpu/media/generic_v4l2_video_device.h",
         "gpu/media/v4l2_image_processor.cc",
         "gpu/media/v4l2_image_processor.h",
         "gpu/media/v4l2_video_decode_accelerator.cc",
@@ -300,6 +298,12 @@ source_set("common") {
         "EGL",
         "GLESv2",
       ]
+      if (cpu_arch == "arm") {
+        sources += [
+          "gpu/media/tegra_v4l2_video_device.cc",
+          "gpu/media/tegra_v4l2_video_device.h",
+        ]
+      }
     }
     if (cpu_arch != "arm") {
       sources += [

content/common/common.gni

@@ -11,3 +11,11 @@ content_common_gypi_values =
                 [ rebase_path("../content_common.gypi") ],
                 "scope",
                 [ "../content_common.gypi" ])
+
+declare_args() {
+  # TODO(henryhsu): This flag should be removed after the linux header of
+  # trybot is updated.
+  # Indicates if Video4Linux2 codec is used. This is used for x86 CrOS
+  # platform which has v4l2 hardware encoder / decoder.
+  use_v4l2_codec = false
+}

content/common/gpu/media/v4l2_video_decode_accelerator.cc

@@ -74,7 +74,7 @@ struct V4L2VideoDecodeAccelerator::BitstreamBufferRef {
   const scoped_refptr<base::MessageLoopProxy> client_message_loop_proxy;
   const scoped_ptr<base::SharedMemory> shm;
   const size_t size;
-  off_t bytes_used;
+  size_t bytes_used;
   const int32 input_id;
 };
 

content/content_common.gypi

@@ -32,6 +32,7 @@
   ],
   'variables': {
     'use_v4lplugin%': 0,
+    'use_v4l2_codec%': 0,
     'public_common_sources': [
       'public/common/appcache_info.h',
       'public/common/bindings_policy.h',
@@ -804,15 +805,13 @@
         },
       ],
     }],
-    ['target_arch=="arm" and chromeos == 1 and use_x11 == 1', {
+    ['chromeos==1 and ((target_arch=="arm" and use_x11==1) or use_v4l2_codec==1)', {
       'dependencies': [
         '../media/media.gyp:media',
       ],
       'sources': [
         'common/gpu/media/generic_v4l2_video_device.cc',
         'common/gpu/media/generic_v4l2_video_device.h',
-        'common/gpu/media/tegra_v4l2_video_device.cc',
-        'common/gpu/media/tegra_v4l2_video_device.h',
         'common/gpu/media/v4l2_image_processor.cc',
         'common/gpu/media/v4l2_image_processor.h',
         'common/gpu/media/v4l2_video_decode_accelerator.cc',
@@ -825,6 +824,14 @@
       'include_dirs': [
         '<(DEPTH)/third_party/khronos',
       ],
+      'conditions': [
+        ['target_arch == "arm"', {
+          'sources': [
+            'common/gpu/media/tegra_v4l2_video_device.cc',
+            'common/gpu/media/tegra_v4l2_video_device.h',
+          ],
+        }],
+      ],
     }],
     ['target_arch != "arm" and chromeos == 1', {
       'dependencies': [